Top earners have captured the big share of all income and wealth gains during the last three decades. They’re where the money is. If we’re to pay for public services they and others want, they must carry a disproportionate share of the tax burden.

The first two sentences are correct statements of fact. The third sentence appears to draw a positive inference from them. Interpreted as such, the sentence is just wrong. Is there any reason to think it is impossible for the government to raise adequate revenue with a proportional tax? Not that I know of, and the article gives no indication of why Frank might think otherwise.

Maybe Frank meant to write "should" rather than "must." In that case, the sentence would have conveyed a personal political opinion, rather than suggesting (incorrectly) a conclusion of economic science. It would have been more clearly labeled as a normative statement.

About Me

I am the Robert M. Beren Professor of Economics at Harvard University, where I teach introductory economics (ec 10). I use this blog to keep in touch with my current and former students. Teachers and students at other schools, as well as others interested in economic issues, are welcome to use this resource.